1. Field of the Invention
The present invention generally relates to a communication between a write/read station of a transponder system and at least one transponder of the transponder system. The present invention specifically relates to a generation of an acknowledge data block and an identification data block during the communication between the write/read station and the transponder.
2. Description of the Related Art
U.S. Pat. No. 5,539,394 A describes a transponder system in which communication between the write/read station and a plurality of transponders takes place, in successive time slots of time slot sequences, communication between the write/read station and a transponder actually taking place exclusively if only a single transponder is associated with each time slot. This is the case when a sole transponder transmits its associated identification data block to the write/read station in a time slot, i.e. if no collision occurs between two or more identification data blocks from two or more transponders in one time slot. In the known transponder system, the write/read station transmits an acknowledge data block to each sole transponder having transmitted its associated identification data block to the write/read station in a time slot, so that each of these transponders is signaled that the write/read station has correctly recognized and hence selected the relevant transponder. As described in the cited patent document U.S. Pat. No. 5,539,394 A, the transmission of the respective acknowledge data block associated with a transponder can take place in the same time slot in which a transponder has transmitted its identification data block to the write/read station. In this case, each acknowledge data block may have the same bit configuration and consist, for example of a predetermined number of xe2x80x9c0xe2x80x9d bits or xe2x80x9c1xe2x80x9d bits, for example one byte with a total of eight xe2x80x9c0xe2x80x9d bits, however, without an own acknowledge data block being associated with each transponder. The cited patent document U.S. Pat. No. 5,539,394 A does not provide further information as regards the bit configuration of the acknowledge data blocks transmitted to the transponders by the write/read station in each time slot.
The cited patent document U.S. Pat. No. 5,539,394 A also describes a second possibility for the transfer of acknowledgements from the write/read station to the selected transponders. This second possibility consists in that acknowledgement takes place at the end of a time slot sequence, consisting of a plurality of time slots, in that at the end of such a time slot sequence a group acknowledge data block and subsequently additionally all identification data blocks of the sole transponders having transmitted their associated identification data block to the write/read station in a time slot in the preceding time slot sequence are transmitted to these transponders by the write/read station. It is thus achieved that for each transponder the write/read station transmits only an acknowledgement exclusively associated with this transponder to this transponder; however each acknowledgement associated with a transponder then consists of the group acknowledge data block and the overall identification data block of the relevant transponder. Consequently, each acknowledgement in the known transponder system has a detrimentally long data block length; this is unattractive with a view to achieving an as short as possible communication time between the write/read station and the plurality of selected transponders, and also with a view to achieving an as small as possible number of modulation steps for the transmission of an acknowledgement from the write/read station to the transponders. An as small as possible number of modulation steps is always desirable, because a comparatively high number of modulation steps has an adverse effect on the level of side bands of the carrier signal occurring during a transmission utilizing a modulated carrier signal; this is because a comparatively high number of modulation steps causes detrimentally high levels of the side bands, giving rise to conflicts in many countries with official rules and regulations which define a maximum permissible level for these side bands.
It is an object of the invention to avoid the described problems and to provide an improved method, an improved write/read station, an improved transponder and an improved integrated circuit.
In order to achieve this object, a method according to the invention is characterized in that in the write/read station an acknowledge data block is generated for each transponder wherefrom an identification data block has been received, the bit configuration of said acknowledge data block being formed while using only a part of the identification data block associated with the relevant transponder.
In order to achieve the described object, a write/read station according to the invention is characterized in that the generating means are arranged to generate a respective acknowledge data block for a transponder, the bit configuration of said acknowledge data block being formable while using only a part of the identification data block associated with the relevant transponder.
In order to achieve the described object, a transponder according to the invention is characterized in that the transponder includes generating means for generating the acknowledge data block associated with the transponder, and that the transponder includes comparison means which can be supplied with the acknowledge data block generated by the generating means and with the acknowledge data block transmitted by a write/read station and received by the transponder, and can output at least control information representing the comparison result.
In order to achieve the described object, an integrated circuit according to the invention is characterized in that the circuit includes generating means for generating the acknowledge data block associated with the circuit, and that the circuit includes comparison means which can be supplied with the acknowledge data block generated by the generating means and with the acknowledge data block transmitted by a write/read station and received by the circuit, and can output at least control information representing the comparison result.
Using only simple means, the steps according to the invention simply ensure that, in order to acknowledge the selection of a transponder according to the invention, an acknowledge data block which is associated only with the relevant transponder is transmitted from a write/read station according to the invention to a relevant transponder according to the invention; the foregoing is advantageously achieved by means of an acknowledge data block having only a short data block length, which is advantageous with a view to achieving an as short as possible communication time or transmission time and also with a view to achieving as few as possible modulation steps for the transmission.
These and other aspects of the invention will be apparent from the embodiment described hereinafter.